This invention relates to the field of smoke generators, and in particular to portable smoke generators for use as training devices. More particularly, the invention relates to smoke generators wherein a smoke producing agent passes through thermally conductive coils and is thus heated to produce smoke. In still greater particularity, the invention may be described as a smoke generator having a series of thin walled tubular coils which also serve as electric current conductors and hence produce differential heating to prolong duration of smoke generation, each coil having a cross-sectional area, length, and electrical resistance selected to provide storage of, motive forces to, and heat transfer to, a smoke producing liquid contained therein.
Training of personnel in emergency response procedures, such as firefighting, is a continual process of particular importance to those engaged in maritime commerce, public safety, and the armed services, especially the Navy. Small smoke generators currently available are not acceptable for shipboard training or training in confined structures such as barracks or dormitories. The Mark 7 smoke pot is the standard military pyrotechnic smoke generator, and a 3-minute smoke bomb made by the Superior Signal Co. is also used. These are disposable non-resuable units which can be quite expensive. Commercial smoke generators which are electrically operated are available, but are too large for surprise drills, and are generally of low capacity due to lack of effective thermal design.
The portable smoke generator of U.S. Pat. No. 4,326,119 is the closest prior art, it being the experimental predecessor of the instant invention; however, it has been determined that for effective training, a smoke must be generated for a greater length of time than was possible with the battery operated generator. Other smoke generators have been devised, such as those disclosed in U.S. Pat. Nos. 3,234,357; 3,990,987; and 3,891,826, which have some characteristics common to the instant invention due to the immutable principles of thermodynamics and fluid flow; however, these generators are generally designed for special purpose applications. Therefore, their design and function are somewhat inappropriate for the instant device, which is believed to provide a patentably improved smoke generator.